Electric heating apparatus for heating a liquid by electrical conduction

ABSTRACT

Electric heating apparatus for electrically conductive fluids, particularly mineralized tap water, includes inner and outer electrodes spaced apart and concentric with one another and shaped to define an annular flow passage which converges progressively to decrease in fluid-carrying volume toward the outlet end. A separate voltage is applied to one or both of the electrodes and the casing surrounding and supporting the electrodes is of an electrically non-conductive material with a metal pipe coupled thereto at ground potential so that a separate current flow path may be established from each electrode to ground via the fluid. The inner electrode is axially adjustable to vary the size of the passage to change the heating effect. A bias member urges the inner electrode to a position of minimum spacing between electrodes and a temperature responsive device downstream of the electrodes moves the inner electrode against the bias member to automatically adjust the spacing between the electrodes in accordance with fluid temperatures to maintain a uniform heating effect. A flow responsive member automatically opens and closes the circuit to the electrodes in response to fluid flow through the flow passage and a thermal switch in power line prevents excessive heating.

United States Patent 1191 11 1 3,867,610

Quaintance 1 Feb. 18, 1975 1 ELECTRIC HEATING APPARATUS FOR 481,5226/1953 Italy 219/291 ING IQ I BY ELECTRICAL 815,368 4/1937 France219/291 CONDUCTION Primary Exam1r1er-A. Barns [75] Inventor: c ii fQuamtance- Tahoe Attorney, Agent, or Firm-Ancel W. Lewis, Jr.

[73] Assignee: Harry M. Rubenstein, Phoenix, ABSTRACT Ariz. Electricheating apparatus for electrically conductive [22] Fied, Dec 17 1973fluids, particularly mineralized tap water, includes inner and outerelectrodes spaced apart and concen- [2l] Appl. No.: 425,078 tric withone another and shaped to define an annular flow passage which convergesprogressively to decrease in fluid-carrying volume toward the outletend. [52] U.S. Cl 219/286, fizz/55329652139438? A separate voltage is ppto one or both of the [51] Int Cl H65) 3/60 electrodes and the casingsurrounding and supporting [58] Fie'ld "gi the electrodes is of anelectrically non-conductive ma- 338/8O 86 terial with a metal pipecoupled thereto at ground potential so that a separate current flow pathmay be es- [56] References Cited tablished from each electrode to groundvia the fluid. The inner electrode is axially adjustable to vary theUNITED STATES PATENTS size of the passage to change the heating effect.A bias 1.l7l,929 2/1916 Cubitt -2 19/288 X member urges the innerelectrode to'a position of min- Meliew t t imum spacing betweenelectrodes and a temperature gi responsive device downstream of theelectrodes moves 2403334 7/1946 z 2194291 X the inner electrode againstthe bias member to auto- 2444'5O8 7/1948 Homim 219/293 X maticallyadjust the spacing between the electrodes in 25/2133? 10/1951Harris...:.:.:: 12.... 219/285 accordance with fluid temperatures tomaintain a 2,618,732 11/1952 Bernd 219/285 x form heating effect A flowresponsive member aulo' 2,748,253 5/1956 Bremer 219/285 UX maticallyopens and closes the circuit to the electrodes 3,796,857 3/1974 Henleyet al 219/286 X in response to fluid flow through the flow passage and3,809,856 5/1974 Wills 219/286 3 h mal switch in power line preventsexcessive FOREIGN PATENTS OR APPLICATIONS heatmg- 1,033,336 4/1953France 219/291 3 Claims, 5 Drawing Figures Will-ll IIIII/IIIIIIIIIIIIIIIII/II/I' ELECTRIC HEATING APPARATUS FOR HEATING A LIQUID BYELECTRICAL CONDUCTION This invention relates to electric heaters forheating electrically conductive fluids and more particularly to a noveland improved electric heating apparatus particularly suitable forheating electrically conductive fluids such as tap water.

A variety of electric heaters utilizing the ohmic dissipation within afluid, and particularly water, have heretofore been provided. Theseheaters rely on the fact that ordinary tap water is heavily mineralizedand the fact that a voltage applied to the water will cause current flowtherethrough. One problem with heating apparatus of this type resides inelectroplating of the electrodes and further there is difficulty inproviding a uniform heating with a minimum of adjustments and control.There is also a tendency for the fluid to rapidly boil away from theelectrodes.

Accordingly, it is an object of this invention to provide improvedelectric heating apparatus for electrically conductive fluids which issimple in construction, durable and will rapidly raise the temperatureof the fluids passing therethrough in a safe and efficient manner.

Another object of this invention is to provide novel electric heatingapparatus for electrically conductive fluids which always returns to aposition of minimum passage width or gap and adjusts automatically tomaintain uniform heating temperatures.

Yetta further object of this invention is to provide novel electricheating apparatus particularly suitable for heating tap water and thelike that will operate on 110 volt or 220 volt electric systems and willprevent plating or mineralization build-up on the currentcarryingelectrodes.

Still a further object of this invention is to provide novel andimproved electric heating apparatus with control means for automaticallyturning off the electric power from a source when the fluid fluid stopsand connecting power to the electrodes when fluid flow begins as well asremoving the electric power when the temperature of the fluid isexcessive.

Still a further object of the invention is to provide a novel andimproved electric heating apparatus for fluids characterized by innerand outer electrodes which define a converging passage thatprogressively decreases in fluid-carrying volume toward the outlet endto prevent the water from boiling away between the electrodes andfurther may utilize a temperatureresponsive device downstream of theelectrodes to automatically adjust the spacing between the electrodes toregulate the heating.

In accordance with the present invention in a preferred embodiment shownthere is provided an outer electrically non-conductive casing, a hollow,truncated cone-shaped outer electrode mounted in the casing and atruncated cone-shaped inner male electrode spaced from and concentricwith the outer electrode providing an annular flow passage therebetweenwith the flow passage converging toward the outlet end to progressivelydecrease in fluid-carrying volume. A separate AV voltage is applied toat least one or both of the inner and outer electrodes, preferably about110 volts AC on each electrode, so that with a grounded metal fluidconductive pipe being connected to the casing and at ground potentialthe fluid in the passage conducts the current flow from each electrodeto ground thereby preventing plating or mineralization of theelectrodes. The inner electrode is axially movable relative to the outerelectrode and is automatically moved by a bimetallic member to adjustthe spacing between the electrodes to maintain the fluid at a desireduniform temperature and a bias member automatically returns the innerelectrode to a position of minimum spacing between electrodes. Aflow-actuated member downstream of the electrodes and connected to aswitch in the power circuit to the electrodes automatically closes thecircuit when there is fluid flow through the passage. A thermostat-typeswitch may be used to disconnect the electric power when the temperatureis excessive.

Other objects, advantages and capabilities of the present invention willbecome more apparent as the description proceeds taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a sectional view of a heater unit embodying features of thepresent invention;

FIG. 2 is sectional view taken along lines 22 of FIG. 1;

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 1;

FIG. 3A is a fragmentary sectional view taken along lines 3A-3A of FIG.1; and

FIG. 4 is a schematic diagram showing the heating apparatus utilized inthe heater unit shown in FIGS. 1-3.

Referring now to the drawings, there is shown in FIGS. l-3A an electricheater unit generally designated 10 which generally comprises a casing11 made as an integral unit of an electrically non-conductive material,preferably a molded plastic having a hollow cylindrical body with endportions 12 and 13 at opposite ends thereof. Internally threadedapertures 14 and 15 are formed in the end portions 12 and 13,respectively, to define a flow inlet and flow outlets, respectively.These internally threaded end portions make the ends of the casingsuitable for coupling to the male externally threaded fittings on theends of fluid conduits or flow lines.

Within the casing 11 there is mounted an electrically conductive sleeve18 of copper, brass or the like which surrounds and provides a supportfor an outer female electrode 21. The outer female electrode 21 hashollow and truncated cone-shaped inner annular surfaces which convergesinwardly toward the outlet end thereof. An inner male electrode 22 ismounted within the outer electrode which is also truncated coneshapedouter annular surface which converges inwardly toward the outlet end sothat the exterior surfaces of inner and outer electrodes will define anannular heating passage or chamber '23 which converges toward the outletend so that the fluid-carrying volume of the passage progressivelydecreases from the inlet to the outlet and is tapered and sized toprevent the boiling away or vaporization of the conductive fluid as itis heated in and passes through the passage. The inner electrode 22 ispreferably made of carbon and has a solid conductive shaft 24 extendingthrough the center thereof. The shaft has threaded end portions 24a and24b at opposite ends extending beyond the ends of the carbon body.

The inner electrode 22 is supported in such a way as to be guidedconcentrically along the longitudinal axis of the casing by means ofthree circumferentially spaced cylindrical or rodlike guides 25. Theseguides are arranged so that the upstream end portion of the innerelectrode 22 slides along in a guided axial movement, as best seen inFIG. 3. The inner and outer elec trodes terminate in a spaced relationto end wall 12 to form an upstream chamber 26 in the casing 11 locatedupstream of the electrodes.

A disc-shaped support member 27 is provided in the casing downstream ofthe electrodes. Member 27 has a central aperture 27a and fourcircumferentially arranged and spaced apart apertures 27b. A cylindricalguide 28 is threaded on the end of the shaft 24 on the outside of a nut29 holding the shaft 24 to the inner electrode. Guide 28 extends throughthe central aperture 27a and is slidable relative thereto so as tosupport the downstream end of the inner electrode for guided slidingmovement in a coaxial relationship with the outer electrode. Thecircumferentially spaced apertures 27b permit the flow of the fluidtherethrough. The inner and outer electrodes terminate in a spacedrelation to the end wall 13 to form a downstream chamber 30 in thecasing downstream of the electrodes.

An electric terminal connector for the outer electrode 21 is provided bya bolt 31 having an outer externally threaded end portion 31a and aninner externally threaded end portion 31b. The bolt 31 extends throughapertures in the casing 11 and conductive sleeve 18 and threads into theouter electrode 21 to make an electrical connection with the outerelectrode 21. A washer 32 and electric line 33 are secured to the outerthreaded end portions 31a by a nut 34.

An electricterminal connector for the inner electrode 22 is provided bya bolt 36 having an externally threaded outer end portion 36a. Boltextends through an aperture in the casing and an electric line 38 andwasher 37 are secured to the threaded portion 360 externally of thecasing by a nut 39. An inner insulated electric line 41 is connectedbetween the bolt 36 and the threaded shaft end portion 24a. Electricline 41 is secured to shaft 24 by a nut 43 with a washer 42 between thenut and carbon body in the upstream chamber 26. An insulator cap 44covers the connection on bolt 36 and an insulator cap 45 covers theconnection to shaft 24 within the upstream chamber 26 to prevent thefluid from short-circuiting the electric connectors.

A temperature-responsive or temperature-sensitive device 46 is mountedwithin the casing in the downstream chamber 30 to sense the heatedfluid. Device 46 is a bi-metal spring comprised of two layers 47 and 48that have different rates of thermal expansion. The shape of device 46is essentially two backward S-shapes connected at the bottom and one ofthe downturned end portions is affixed to guide 28 and the otherdownturned end portion 56 is supported by a disc 50 with flow apertures50a downstream of disc 27 and when device 46 heats, the end portionsthereof move in such a way as to push the inner electrode 22 in theupstream direction against the forces of a return spring 49 in upstreamchamber 26 to adjust the spacing or passage 23 between the electrodes inaccordance with the fluid temperature. The return spring 49 returns theinner electrode to the position of minimum spacing between theelectrodes.

A flow-actuated member 51 in the form of a circular flap is pivotallymounted in downstream chamber 30 and is responsive to the flow of fluidthrough the passage. The flap has a central aperture permitting it toslide over guide 28 and is mounted on a pin 52 extending through a wallof the casing. The pin 52 rotates freely permitting the member 51 toswing freely toward the downstream end when there is fluid flowingthrough the passage. As shown in FIG. 4, the pivot pin 52 is coupled toa pair of rotary contact arms 54 and 55 of a rotary switch arranged inthe power circuit for controlling the electric power to the electrodes.A 220 volt AC electric power source or supply represented at 56 for thesystem comprises a conventional three-wire source with input lines 57and 58 each having a separate 110 volt AC and the third ground line 58being connected to a ground. Active lines 57 and 58 connect to contactarms 54 and 55, respectively, through contact arms 61 and 62,respectively, of a manual electric control switch. In turn, contact arms54 and 55 connect to terminals 38 and 33, respectively, on the heatercircuit. A temperature-sensitive thermostat-type switch or thermostat T1is shown connected in line 57 and similar switch or thermostat T2 inline 58. These switches are located in the casing and open when thetemperature of the heated fluid becomes excessive and automaticallyclose when the temperature drops back below a selected maximumtemperature such as l60F. The heater unit 10 is shown in FIG. 4 as beingcoupled between a supply conduit receiving fluid from a source and anoutlet valve on faucet 66 with the supply conduit being shown aselectrically grounded as is the case for most pipe systems.

In a full sequence of operation for the system shown in FIG. 4, then thecontact arms 61 and 62 of the control switch are closed and valve 66 isopened to provide a fluid flow through the heater casing. Contacts 54and 55 close and the power circuit applies a separate AC voltage to eachof the electrodes 21 and 22. The passage 23 between the electrodes isheld by a spring 49 to a minimum gap for the fastest heating switch andthe passage gradually widens and increases flow as the fluid is broughtup to the desired temperature. As the temperature of the fluidincreases, the device 46 will press against the plunger 28 moving theinner electrode 21 in toward the upstream end and thereby widening theflow passage. In this way a substantially uniform temperature ismaintained for the fluid flowing through the passage. Once the flowcontrol valve 66 is closed the fluid flow through the passage stops,member 51 rotates to move the contact arms 54 and 55 to an open positionand open the power circuit which remains open until the control valve 66is again opened and the heating procedure is repeated.

For some applications when only one volt line is available or that isall the power that is required then line 33 may be connected to groundand the live power line terminal is connected to line 38 as shown inFIG. 4. Conversely, this could be reversed by grounding line 38 andapplying the live power line to terminal 33.

From the foregoing it is apparent that the heating apparatus abovedescribed utilizing a non-conductive casing and an electric voltage toat least one electrode will cause current flow from the electrode toground via the water. This has been found to materially reduceelectroplating or mineral build-up on the electrodes. The utilization ofa heater passage which converges toward the outlet and progressivelydecreases in fluid-carrying volume toward the outlet in effectcompresses the water and helps to avoid loss of fluid due tovaporization. The automatic adjustment of the spacing in accordance withfluid temperature affords close regulation of discharge temperature. Itis also apparent that several of the heater units may be connected inseries in a flow line to heat larger volumes and raise the temperaturesmore rapidly, if required. An optional feature would be a manualadjustment of the spacing between the inner and outer electrodes byusing a threaded screw extending axially through the end of the housingand into the inner electrode 22. Further, it is apparent that thevoltage to the electrodes may be adjusted to vary the temperature rangeof the fluid.

Although the present invention has been described with a certain degreeof particularity, it is understood that the present disclosure has beenmade by way of example and that changes in details of structure may bemade without departing from the spirit thereof.

What is claimed is:

1. Electric heating apparatus for heating electrically conductive fluidscomprising:

an outer casing of an electrically non-conductive material having endportions defining a flow inlet and flow outlet,

a hollow, outer female electrode, disposed within said outer casing andhaving a truncated coneshaped inner surface,

and inner male electrode having a truncated coneshaped outer surfacedisposed in the outer electrode spaced from and concentric with saidouter electrode surface to provide an annular flow passage therebetweenhaving a selected gap width, said outer female and inner male electrodesurfaces converging from the inlet end to the outlet end to decrease thefluid-carrying volume of said passage toward the outlet end therebypreventing the fluid from boiling away as it passes through said flowpassage,

power circuit means for applying an electric voltage to at least one ofsaid outer female and inner male electrodes using the fluid in thepassage as a conductor to ground potential for the current flowof eachof said electrodes to ground potential through the fluid to preventelectroplating of the electrodes,

support means at both the upstream and downstream ends of the inner maleelectrode for supporting said inner male electrode for axially alinedmovement while maintaining concentric uniformity in the annular flowpassage, said support means including a plurality of circumferentiallyspaced guides in the upstream end of the casing engaging the peripheryof the inner male electrode and a downstream support in the downstreamend of the casing supporting an extension of the inner male electrode,and

axial positioning means for positioning the inner male electrode at aposition of minimum spacing and axially moving the male electrodeinclusive of a temperature responsive member downstream of theelectrodes to automatically adjust the spacing be tween the inner andouter electrodes in response to the temperature of the fluid to maintaina substantially uniform heating effect for the fluid.

2. Electric heating apparatus as set forth in claim 1, wherein saidaxial positioning means includes a fluid temperature responsivebi-metallic member having an essentially double backward S-shape in thedownstream end of the casing to automatically adjust the spacing betweenthe electrodes in response to a temperature change in the fluid.

3. Electric water heating apparatus comprising:

an outer casing made of a plastic material and further including aninner metal sleeve, said casing having end portions defining a flowinlet and flow outlet at the end of the casing,

supply conduit means coupled to the flow inlet end of the casing at aground potential,

a flow control valve coupled to the outlet end of the casing,

an outer female electrode having a truncated coneshaped inner surfacemounted in said outer casing.

an inner male electrode having a truncated coneshaped inner surfacespaced from and concentric within said female outer electrode to providean annular flow passage therebetween of a selected gap width, saidsurfaces of the electrodes converging from the inlet end to the outletend to decrease the fluid-carrying volume toward the outlet end therebypreventing the fluid from boiling away as it passes through said flowpassage,

support means at both the upstream and downstream ends of the inner maleelectrode for supporting said inner male electrode for axially alinedmovement while maintaining concentric uniformity in the annular flowpassage, said support means including a plurality of circumferentiallyspaced guides in the upstream end of the casing engaging the peripheryof the inner male electrode and a support in the downstream, end of thecasing supporting an extension of the inner male electrode,

axial positioning means for positioning the inner male electrode at aposition of minimum spacing and axially moving the male electrodeinclusive of a temperature responsive member downstream of theelectrodes to'automatically adjust the spacing between the inner andouter electrodes in response to the temperature of the fluid to maintaina substantially uniform heating effect for the fluid, said axialpositioning means for the inner male electrode including a bias springin the upstream end of the casing urging the inner electrode to a,position of minimum spacing and a fluid temperature responsivebi-metallic spring attached at one end and having the other end affixedto the extension on the inner male electrode to automatically adjust thespacing between the electrodes in response to temperature change in thefluid,

AC power circuit means for applying a separate AC voltage to each ofsaid inner male and outer female electrodes using the water passingthrough the flow passage as a conductor to the ground potential at saidsupply conduit means for current flow from each of said electrodes tothe ground potential to prevent electroplating of the electrodes,

flow actuated means in the casing downstrea, of the electrodes coupledto the power circuit means to automatically close AC power circuit meanswhen the flow control valve is opened and automatically open the powercircuit means when the flow control valve is closed and thermostatswitch means to automatacally open said AC power circuit when thetemperature of the heated fluid exceeds a preselected maximum amount.

1. Electric heating apparatus for heating electrically conductive fluidscomprising: an outer casing of an electrically non-conductive materialhaving end portions defining a flow inlet and flow outlet, a hollow,outer female electrode, disposed within said outer casing and having atruncated cone-shaped inner surface, and inner male electrode having atruncated cone-shaped outer surface disposed in the outer electrodespaced from and concentric with said outer electrode surface to providean annular flow passage therebetween having a selected gap width, saidouter female and inner male electrode surfaces converging from the inletend to the outlet end to decrease the fluidcarrying volume of saidpassage toward the outlet end thereby preventing the fluid from boilingaway as it passes through said flow passage, power circuit means forapplying an electric voltage to at least one of said outer female andinner male electrodes using the fluid in the passage as a conductor toground potential for the current flow of each of said electrodes toground potential through the fluid to prevent electroplating of theelectrodes, support means at both the upstream and downstream ends ofthe inner male electrode for supporting said inner male electrode foraxially alined movement while maintaining concentric uniformity in theannular flow passage, said support means including a plurality ofcircumferentially spaced guides in the upstream end of the casingengaging the periphery of the inner male electrode and a downstreamsupport in the downstream end of the casing supporting an extension ofthe inner male electrode, and axial positioning means for positioningthe inner male electrode at a position of minimum spacing and axiallymoving the male electrode inclusive of a temperature responsive memberdownstream of the electrodes to automatically adjust the spacing betweenthe inner and outer electrodes in response to the temperature of thefluid to maintain a substantially uniform heating effect for the fluid.2. Electric heating apparatus as set forth in claim 1, wherein saidaxial positioning means includes a fluid temperature responsivebi-metallic member having an essentially double backward S-shape in thedownstream end of the casing to automatically adjust the spacing betweenthe electrodes in response to a temperature change in the fluid. 3.Electric water heating apparatus comprising: an outer casing made of aplastic material and further including an inner metal sleeve, saidcasing having end portions defining a flow inlet and flow outlet at theend of the casing, supply conduit means coupled to the flow inlet end ofthe casing at a ground potential, a flow control valve coupled to theoutlet end of the casing, an outer female electrode having a truncatedcone-shaped inner surface mounted in said outer casing, an inner maleelectrode having a truncated cone-shaped inner surface spaced from andconcentric within said female outer electrode to provide an annular flowpassage therebetween of a selected gap width, said surfaces of theelectrodes converging from the inlet end to the outlet end to decreasethe fluid-cArrying volume toward the outlet end thereby preventing thefluid from boiling away as it passes through said flow passage, supportmeans at both the upstream and downstream ends of the inner maleelectrode for supporting said inner male electrode for axially alinedmovement while maintaining concentric uniformity in the annular flowpassage, said support means including a plurality of circumferentiallyspaced guides in the upstream end of the casing engaging the peripheryof the inner male electrode and a support in the downstream, end of thecasing supporting an extension of the inner male electrode, axialpositioning means for positioning the inner male electrode at a positionof minimum spacing and axially moving the male electrode inclusive of atemperature responsive member downstream of the electrodes toautomatically adjust the spacing between the inner and outer electrodesin response to the temperature of the fluid to maintain a substantiallyuniform heating effect for the fluid, said axial positioning means forthe inner male electrode including a bias spring in the upstream end ofthe casing urging the inner electrode to a position of minimum spacingand a fluid temperature responsive bi-metallic spring attached at oneend and having the other end affixed to the extension on the inner maleelectrode to automatically adjust the spacing between the electrodes inresponse to temperature change in the fluid, AC power circuit means forapplying a separate AC voltage to each of said inner male and outerfemale electrodes using the water passing through the flow passage as aconductor to the ground potential at said supply conduit means forcurrent flow from each of said electrodes to the ground potential toprevent electroplating of the electrodes, flow actuated means in thecasing downstrea, of the electrodes coupled to the power circuit meansto automatically close AC power circuit means when the flow controlvalve is opened and automatically open the power circuit means when theflow control valve is closed and thermostat switch means toautomatacally open said AC power circuit when the temperature of theheated fluid exceeds a preselected maximum amount.